//计算阶乘
 var oneStr = 'testString';

//var changeStr = function(str) {
//    oneStr = str;
//}

var factorial = function(n) {
    if (n < 0)
        return;
    if (n === 0)
        return 1;
    return n * factorial(n - 1)
};

var add = function (a,b) {
    return a + b;
}
